N20 Tuning and grounding out the IAT question
#41
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Originally Posted by Frost
Yes; it should work quite well for this, but it would act like a wet kit (ie low bottle pressure would result in richer fueling) as far as bottle pressure goes. Also you would have to begin by flashing your car with an 01/02 OS to get the PE modifier vs IAT.
Keep us updated! This sounds awesome!
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#43
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Originally Posted by Frost
I'm going to (when nitrous is armed) "replace" the IAT with a fixed resistor that forces the IAT into thinking it's as low as it can go. As far as I can see, outside of startup, the IAT at WOT only is examined in 1 table. That table exists solely to pull timing if very high IATs are reached; most of the table is 0. The table adds to your current spark map. Once the resisitor is brought in, we are locked on the far left of the table (IATs of 14degF, single coulmn) where you wouldn't normally end up (maybe if you live in Antarctica) and in these 3-4 cells (80ish kpa and up) you set the retard you want to have active while the nitrous is armed and it is subtracted from your ideal N/A timing table.
Keep your peak N/A tune and automatically pull timing just for nitrous without something that is intercepting the CPS and delaying it... and also costing a bunch of money.
Keep your peak N/A tune and automatically pull timing just for nitrous without something that is intercepting the CPS and delaying it... and also costing a bunch of money.
BTW, I believe the guys that tune for dry shots use a different method and also now you can use a custom nitrous operating system with EFI live to do the same thing now.
![](http://i117.photobucket.com/albums/o48/SmaknaSS/SparkvsIAT.jpg)
[IMG]
![](http://i117.photobucket.com/albums/o48/SmaknaSS/BMN_timingpullWTrimpot.jpg)
Last edited by SmaknaSS; 08-25-2007 at 10:29 PM.
#44
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I'm using the resistor to put it to the bottom of the table though, when you move it upwards (remember fueling is based on an IAT/ECT bias table) you affect fueling, leaning out somewhat... that's why I push it low (bottom scale) rather than raise it to what could be a real area. Also doing it like this, you don't EFIL, you can use any tuning suite to make it work.
The item I've put together is a nice unit, GM-spec'd metri-pack connectors to keep you from having to cut up your factory harness and has an LED on the output side so that if the unit fails, it's indicator will not light up, and the input side (+12v feed from the nitrous arming ckt) is fused for protection![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
Also, you must have a late model car, the pre 01 models are referenced against MAP rather than dynamic air.
The item I've put together is a nice unit, GM-spec'd metri-pack connectors to keep you from having to cut up your factory harness and has an LED on the output side so that if the unit fails, it's indicator will not light up, and the input side (+12v feed from the nitrous arming ckt) is fused for protection
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Also, you must have a late model car, the pre 01 models are referenced against MAP rather than dynamic air.
#45
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Originally Posted by Frost
I'm using the resistor to put it to the bottom of the table though, when you move it upwards (remember fueling is based on an IAT/ECT bias table) you affect fueling, leaning out somewhat...
![](http://i117.photobucket.com/albums/o48/SmaknaSS/PEbasedonintaketemp.jpg)
I don't dought you and I'm sure you know more than I do but I have never noticed an IAT effect on my fueling during PE.
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#47
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Originally Posted by SmaknaSS
Are you talking about this table?
I don't dought you and I'm sure you know more than I do but I have never noticed an IAT effect on my fueling during PE.
Sorry for the questions, I'm just trying to learn.
I don't dought you and I'm sure you know more than I do but I have never noticed an IAT effect on my fueling during PE.
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Originally Posted by Jpr5690
Why Not Just Put The Iat sensor Right Infornt Of The N20 Bloom.. You Will Get Your 14 Deg Iat With No Resistir Needed..
#49
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Originally Posted by Frost
No, it effects fueling outside of PE actually (look for a bias table with IAT/ECT), it drives trims more negative if placed low and drives them positive if you use the high side of the table, but I don't know how far (it changes about 2-5% down low), I just wouldn't want it to allow positive trimming.
Thanks.
#50
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Yeah that works, it's just one offset for all of PE though. The table I am actually referring to is Cylinder Charge Temperature Bias Vs. Airflow. Numbers closer to 1 put the bias more towards ECT rather than IAT, though I don't reccommend you touch this unless you REALLY know what you are doing. I have messed with it some on SD tunes but can't seem to get the desired effect so I generally leave it stock. It really contributes to the inability to get a SD tune PERFECT all around.